Major U.S. utility Southern Co. said it has agreed to design and build an advanced demonstration nuclear reactor at Idaho National Laboratory (INL) using technology developed by TerraPower, the Bill Gates-backed company that earlier this week announced it would site a new Natrium nuclear reactor demonstration project in Wyoming.

Southern in a Nov. 18 news release said it would build a molten-chloride reactor at INL. The U.S. Dept. of Energy (DOE) is providing a five-year grant to cover 80% of the $170 million project, with the rest coming from Southern, TerraPower, and other investors.

“Southern Company is committed to advancing next-generation nuclear as part of a comprehensive strategy to deliver clean, safe, reliable, affordable energy to the customers we’re privileged to serve,” said Dr. Mark S. Berry, Southern Co. Vice President of Research and Development. “The Molten Chloride Reactor Experiment will support the commercialization of a revolutionary technology on a timescale that addresses climate change benchmarks and delivers on Southern Company’s goal of net-zero greenhouse gas emissions by 2050. We’re honored to work with DOE and our many industry team members on this truly groundbreaking experiment.”

Companies Designing Smaller Reactors

Southern recently discussed its program for small nuclear reactors at POWER’s Distributed Energy Conference in San Antonio, Texas, in October, in a session that included Clint Medlock, Project Manager-Research and Development for Southern, and Shannon Brigg-Sitton, lead of the Integrated Energy Systems team at INL. Southern and TerraPower are among several companies worldwide seeking to build smaller reactors, often in scalable modular designs, that could be built faster and more cost-effectively than larger, conventional nuclear power plants.

Lauren Lathem, Southern’s program manager, on Thursday said the demonstration project at INL would have less than 50 kW of generation capacity and is expected to go into service in 2026. A commercial version of the reactor could eventually generate 720 MW of power, according to the company.

The reactor will use TerraPower’s molten-chloride technology, a design that operates at higher temperatures than conventional reactors. Researchers have said that design is more efficient than the current generation of water-cooled reactors. Southern said the molten-chloride technology is a different design from the Natrium liquid-sodium reactor that TerraPower has said it will build in Kemmerer, Wyoming, for PacifiCorp. That project is sited near the Naughton Power Plant, where two coal-fired generating units are expected to be retired in 2025.

Southern on Thursday said “The Molten Chloride Reactor Experiment will provide crucial operational data for fast-spectrum salt reactors and unlock this uniquely flexible advanced reactor technology for use in a net-zero future.” The project was selected for funding under  the DOE’s Advanced Reactor Demonstration Program.

Other companies involved in the INL project include CORE POWER, Orano Federal Services, the Electric Power Research Institute, and 3M. 

First Fast-Spectrum, Salt-Fueled Fission Reactor to Go Critical

Southern said the INL demonstration “will be the world’s first fast-spectrum, salt-fueled nuclear fission reactor to go critical, meaning that it is operating on a self-sustaining nuclear chain reaction. The project represents a significant inflection point in the technology demonstration road map for TerraPower’s MCFR [molten chloride fast reactor], as the project will inform the design, licensing and operation of an MCFR demonstration reactor. An environmental review will be completed for the Molten Chloride Reactor Experiment in accordance with the National Environmental Policy Act before final design and construction begin.”

“Our past work with Southern Company has led to important experimental milestones and to the establishment of unique test facilities necessary to validate molten salt reactor technology,” said Chris Levesque, TerraPower’s president and CEO. “Southern Company’s leadership and experience in reactor licensing and operation has been essential. The Molten Chloride Reactor Experiment will continue this important work in a critical reactor experiment, leading to the successful development of low-cost, clean energy for the future.”

Southern Co. and TerraPower were awarded about $40 million from DOE through a public-private partnership in 2015. The money was earmarked for construction of  integrated infrastructure necessary to support early development of MCFR technology. 

Darrell Proctor is a senior associate editor for POWER (@POWERmagazine).